Electret microphone assemblies are well known in the art. Typically, the assemblies include an electret microphone disposed within a housing. The electret microphone has a diaphragm and a charged plate. Sound vibration vibrates the diaphragm, which vibration generates an electrical signal on the charged plate. Often the housing also contains a substrate. The substrate can support an impedance matching circuit for matching the high impedance of the electret microphone with the relatively lower input impedance of an external amplifier. Alternatively, the substrate can support an internal amplifier, such as that disclosed in the above-incorporated patent.
In either event, the impedance matching circuit and the internal amplifier each have an input terminal which must be coupled to the charged plate. Because of the extremely small dimensions of such microphones, especially as used in hearing aids, coupling the charged plate to the particular input terminal has been difficult.
Applicants' invention is provided to solve this and other problems.